Imagine if you had! You might be the 100X JavaScript writer.

More seriously everyone knows there are patterns that keep repeating themselves from low level on up. The more exposure you get the better you get at understanding them. I think there's a reasonable question about if the best methodology for understanding is to see the same thing repeatedly (that is just study JavaScript) or to see multiple variations on the same thing (that is learn the entire stack imperfectly).

The counter to this in my mind is that learning for it's own sake is often imperfect. If I know I'm learning about semiconductors simply to get on to learning Assembly and then JavaScript (my actual goal) I'll retain less then if the initial steps are the goal itself.

Pedagogy is a tricky thing.